Veterinary
Wilson et al., J Veterinar Sci Technolo 2012, 3:1
http://dx.doi.org/10.4172/2157-7579.1000114
Science & Technology
Research Article
Open Access
Bovine Viral Diarrhea Milk ELISA Test Detecting Anti-p80 Antibody –
Association with Milk Handling Methods and Cow Characteristics
David J. Wilson*, Kerry A. Rood and Gregory M. Goodell
Department of Animal, Dairy, and Veterinary Sciences, Utah State University, Logan, UT 84341 (Wilson, Rood), The Dairy Authority, Greeley, CO 80634 (Goodell), USA
Abstract
A milk ELISA test for Antibody (Ab) against Bovine Viral Diarrhea (BVD) virus was studied in a dairy herd with
past diagnoses of calves dying from BVD and Persistently Infected (PI) cows, with culling of all known PI cows.
Modified live BVD vaccine was administered to calves 3 months and 4 months old, all cows at dryoff 45 to 60 days
before calving, and 15-21 days in milk (DIM). Cows were tested 1 month apart (247 and 258 cows, respectively)
using a competitive ELISA for milk Ab binding to p80 BVD non-structural protein. Results are reported as % binding
by a second Ab; higher second Ab binding means the milk had less anti-p80 BVD Ab. Cows with 90-100% binding
in milk on both tests were classified as low Ab–interpreted as a cow with PI or vaccine failure. Milk handling method
was significant; fresh milk mean 49% second Ab binding was higher than for milk preserved 3 other ways. In fresh
milk, 15 cows had 90-98% binding on one test, but 14/15 were milking during both herd tests and were below 90%
on the other tests. Stage of lactation significantly affected results; anti-BVD Ab was higher from 1-30 DIM and lower
from 61-150 DIM than at other stages of lactation. Ear notches were sampled concurrently from all cows for BVD
antigen capture ELISA testing. Neither the milk ELISA results (no cows > 90% second Ab binding on both milk tests)
nor ear notch testing classified any cows as PI animals. The milk BVD test might be useful to the dairy industry as a
practical and convenient test for screening herd replacements, especially when large numbers of lactating cows are
purchased and mixed into different pens throughout a dairy herd.
Keywords: Antibody; Bovine Viral Diarrhea; ELISA; Milk
Introduction
Bovine Viral Diarrhea (BVD), caused by BVD virus, a pestivirus,
is an important respiratory, gastrointestinal, ocular, and reproductive
tract disease complex of dairy cattle [1-3]. Calves infected with BVD
in utero may be aborted, born malformed, or born apparently normal,
and like calves infected as neonates, may contract diarrhea, respiratory
disease, or neurologic signs [1,2,4,5]. Calves infected from 60 to 120
days of gestation may become Persistently Infected (PI) animals [2,4].
Such PI animals are a small percentage of the dairy cattle population,
often clinically normal, may survive to adulthood, shed large amounts
of BVD virus from bodily secretions throughout their lives, and are the
major source of infections in herdmates resulting in clinical disease,
abortions, and production losses [2,6].
Because they are of low prevalence and high importance, detection
and removal of all PI animals from dairy herds is the single most
effective BVD control measure known to date [2,7]. Many different
tests for BVD using blood, milk (including bulk tank milk for initial
herd screening) or tissues as the sample are available, and numerous
test strategies are used around the world. Tests include indirect or
competitive ELISAs, virus isolation from inoculated bovine cell
cultures, and viral antigen detection ELISAs [7]. Viral antigen capture
ELISA tests have become most popular in the U.S., with skin biopsy in
the form of ear notches being the sample most commonly tested [7,8].
The study reported here evaluated a milk test for BVD commercially
available in the European Union (Idexx, Montpellier, France). The
test is a competitive (blocking) ELISA for detection of milk antibody
(Ab) specific for “BVD p80 Antigen”, p80/125 non-structural
protein, also sometimes called non-structural protein 3, common
to all strains of BVD virus. The principal objectives were to evaluate
potential association of different milk sample handling methods or
cow characteristics such as age and stage of lactation with milk ELISA
results, determine repeatability of consecutive monthly test results,
J Veterinar Sci Technolo
ISSN: 2157-7579 JVST, an open access journal
and test for possible association of anti-BVD Ab with milk production
adjusting for other significant factors.
Materials and Methods
Study herd
A commercial dairy farm in Utah milking approximately 250 cows,
primarily Holsteins but some Jerseys, participated in the study. During
the previous 2 years, 3 calves approximately 3 days old (2 Jerseys, 1
Holstein) that died and for which BVD was diagnosed as the main
cause of death and 2 PI Holstein cows diagnosed by antigen capture
ear notch ELISA (Idexx, Westbrook, ME) were detected in the herd
by testing at the Utah Veterinary Diagnostic Laboratory (UVDL). The
farm had an established practice of culling PI cows; in accordance the
2 cows detected as PI were culled before the study. Modified live BVD
vaccine was administered to 3 and 4 month old calves, 45 to 60 days
before expected date of calving (this was at time of dry off in cows
expecting their 2nd or greater calf), and 15-21 DIM following calving.
Tests and testing schedule
All lactating cows were tested at consecutive monthly Dairy Herd
Improvement Association (DHIA) herd tests (35 days apart). Milk
*Corresponding author: David J. Wilson, Department of Animal, Dairy, and
Veterinary Sciences, Utah State University, Utah Veterinary Diagnostic Laboratory,
950 East 1400 North, Logan, UT 84341, USA, Tel: (435) 760-3731; Fax: (435) 797­
2805; E-mail: David.Wilson@usu.edu
Received March 24, 2012; Accepted May 17, 2012; Published May 22, 2012
Citation: Wilson DJ, Rood KA, Goodell GM (2012) Bovine Viral Diarrhea Milk
ELISA Test Detecting Anti-p80 Antibody – Association with Milk Handling Methods
and Cow Characteristics. J Veterinar Sci Technol 3:114. doi:10.4172/2157­
7579.1000114
Copyright: © 2012 Wilson DJ, et al. This is an open-access article distributed under
the terms of the Creative Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original author and
source are credited.
Volume 3 • Issue 1 • 1000114
Citation: Wilson DJ, Rood KA, Goodell GM (2012) Bovine Viral Diarrhea Milk ELISA Test Detecting Anti-p80 Antibody – Association with Milk
Handling Methods and Cow Characteristics. J Veterinar Sci Technol 3:114. doi:10.4172/2157-7579.1000114
Page 2 of 5
samples were collected using DHIA milk meters, and samples were
chilled and transported in coolers to the UVDL. Samples were shipped
in insulated containers with frozen gel cold packs overnight by courier
to The Dairy Authority (TDA) Laboratory in Greeley, CO. At TDA,
samples were aliquoted and handled in one of 4 ways: fresh milk
(tested the day after collection), no 2-Bromo-2-nitro-1,3-propanediol
(Bronopol, D & F Control Systems, San Ramon, CA) preservative pill;
2 days post-collection milk, preservative pill; milk frozen for 7 days
post-collection, no preservative pill; milk at room temperature for 7
days post-collection, preservative pill. Production and lactation data
on all milking cows was recorded electronically by DHIA, and the
information was transmitted to the investigators.
All adult cows including pre-calving heifers nearing their first
calving were tested for BVD using antigen capture ELISA on ear notch
tissue during the month of the study, between the 2 DHIA visits.
Individual-cow ear notch tissue samples were collected, placed in
sealed and labeled vials, and shipped the same day via overnight courier
to AgSource Laboratories in Jerome, ID for antigen capture ELISA
testing (Idexx, Westbrook, ME) performed as described previously [9].
BVD milk ELISA
The non-structural protein p80/125 (p80), an antigen common
to all strains of BVD virus, was coated onto the walls of 96-well
polystyrene microplates included in the test kit. Milk samples (100
µl) were added to each test well and the plate was covered with an
adhesive plate sealer and incubated for 2 hr at 21ºC. If present, anti-p80
Ab in the milk bound to the p80 BVD antigen in the wells during the
incubation period. Contents of plates were then emptied. Plates were
washed 3 times (wells filled with 300 µl of test kit wash solution using
an automated plate washer). The first wash remained in the wells for
3 minutes, the last 2 washes were emptied immediately, and after the
final wash the inverted plates were struck firmly on a towel on a counter
top. Anti-p80 Ab WB112 coupled to peroxidase (100 µl) was added
to each well and the plate was covered with an adhesive plate sealer
and incubated for 30 min at 21ºC. The more anti-p80 (anti-BVD) Ab
that was present in a milk sample, proportionally less of the second test
kit anti-p80 Ab WB112 could bind to the well during the incubation
period. After plates were emptied and washed 3 times as above, 100
µl of the enzyme substrate 3,3’,5,5’ - Tetramethylbenzidine (TMB)
was added to the wells and incubated for 20 min at 21ºC away from
light. Then100 µl of H2SO4 0.5 M stock solution was added to each
well and plates were gently shaken on a plate shaker until the colored
solution was visibly homogenized. The TMB only binds to the second
peroxidase-coupled Ab, producing a color change (blue to yellow). The
intensity of the color change was read by an ELISA photometric plate
reader at 450 nm (blanked on air) and was an inverse measure of the
level of anti-p80 (anti-BVD) Ab present in the milk samples.
One positive control serum and 2 negative control sera (test kit
reagents) were included on each 96-well plate. The positive control
demonstrated reduced binding by the test kit anti-p80 Ab WB112
(must be no more than 20% of the mean binding of the negative control
samples). The mean of the negative controls provided a reference level
for 100% binding by the test kit anti-p80 Ab WB112 and a corresponding
OD (must have minimum OD450 of 0.8). The lower the OD of a well that
was used to test a milk sample, the more anti-BVD Ab was present in
that sample. Results are expressed as % binding by the second test kit
Ab (BVD%) as measured by the OD of each sample well in proportion
to the mean OD of the 2 negative control wells. Interpretation of the
BVD% binding is as follows: 90-100%, low anti-BVD Ab in cow’s milk
J Veterinar Sci Technolo
ISSN: 2157-7579 JVST, an open access journal
– possible PI or vaccine failure; 60-89%, moderately low anti-BVD Ab;
30-59%, moderate anti-BVD Ab; 10-29%, high anti-BVD Ab; 0-9%,
very high anti-BVD Ab in cow’s milk.
Statistical Analysis
Systat 13 was used for statistical testing. Descriptive statistics,
tests for normality and type of distribution of variables, and analysis
of residuals were performed. Analysis of variance (ANOVA), and if
significant differences were indicated, Tukey’s multiple comparison
test for differences in means of continuous variables among categorical
variables (groups) were used. Correlation between 2 continuous
variables was performed. General linear models (GLM) were used
to evaluate the association of potential explanatory variables with a
continuous outcome variable of interest such as milk production.
Logical potential explanatory variables and possible interactions were
tested and only significant variables were included in the final model.
Level of statistical significance used was α = 0.05.
Results
During the 2 consecutive monthly DHIA herd visits, 247 and 258
cows were milk sampled. There were 226 cows that were milking on
both test days and were sampled twice.
Negative controls (reference level for 100% binding by the test
kit anti-BVD Ab; must have minimum OD of 0.8) had mean OD of
1.73 (range 1.36 – 2.10). Positive controls (must have mean BVD%
[binding] no more than 20%) had mean OD of 0.08 (range 0.07 – 0.10),
with mean BVD% of 4.8% (range 4.1% - 5.2%). BVD% differed among
the 4 milk handling methods (P < 0.001, ANOVA), however the only
significant difference was between the 2 milk handling methods with
the highest and lowest BVD%, fresh milk and room temperature for 7
days with preservative pill, respectively (Tukey’s, P < 0.01). Means for
BVD% were as follows (means with the same superscript letter are not
significantly different from each other): fresh milk, no preservative pill
49%a; 2 day old milk with preservative pill 45%ab; sample frozen for 7
days, no preservative pill 45%ab; sample at room temperature for 7 days
with preservative pill 42%bc. Also, no cows with >90% BVD% (low antiBVD Ab) cows were detected with any sample type except fresh milk
with no preservative.
Correlation between BVD% values for the same cows using
different milk sampling methods was determined for each combination
of 2 handling methods (n = 505 cows) and also for the 2 monthly test
values for the 226 cows tested twice. Correlation of BVD% between
any 2 milk sample handling methods or consecutive DHIA tests using
the same method was always approximately r = 0.65. The pattern
was always observed that for low BVD% cows (high Ab), there was a
stronger relationship between differently handled milk samples than
for high BVD% cows (low Ab) (Figure 1 and Figure 2).
The remaining results are shown for fresh milk with no preservative
only. The BVD% ranges for the 2 months were 3-98% and 4 - 96%.
Quartiles were 29%, 47%, 62% 1st mo, 35%, 56%, 71% 2nd mo; the
distribution of BVD% values was approximately normal (Figure 3 and
Figure 4).
There were 15 cows with 90-98% BVD%, in the range that is
interpreted that they are possibly PI cows or vaccine failures: 4 cows
during the first month (96 - 98% BVD%) and 11 cows during the second
month (90 - 96% BVD%). This represents 5.3% (15/279) of all cows
tested at least once, and 3.0% (15/505) of all BVD tests during the 2
mo. However, 14 of those 15 cows were tested during both months (all
Volume 3 • Issue 1 • 1000114
Citation: Wilson DJ, Rood KA, Goodell GM (2012) Bovine Viral Diarrhea Milk ELISA Test Detecting Anti-p80 Antibody – Association with Milk
Handling Methods and Cow Characteristics. J Veterinar Sci Technol 3:114. doi:10.4172/2157-7579.1000114
Page 3 of 5
Figure 1: Values of milk anti-p80 BVD Ab binding % from fresh milk with no
Bronopol preservative pill (x-axis) compared to milk stored at room tempera­
ture for 7 days with preservative pill (y-axis) from the same cows. Correlation
between combinations of 2 sample handling methods (there were 4 differ­
ent sample handling methods) was always close to r = 0.65, the correlation
shown here. The pattern was always evident that for low BVD Ab binding %
values (higher anti-p80 BVD Ab in milk), there was a stronger relationship
between differently handled milk samples than for high BVD Ab binding %
values (lower anti-p80 BVD Ab in milk) as shown in the upper right corner.
Figure 3: Values of milk anti-p80 BVD Ab binding % were approximately
normally distributed. Values shown are for August Ab binding % in fresh
milk with no Bronopol preservative pill.
Figure 4: Values of milk anti-p80 BVD Ab binding % plotted against total
fraction of all cows accounted for as values increased (Ab in milk of cows is
inversely related; higher %’s indicate less Ab in cows’ milk). The 11 cows in
the upper right corner are the 11 cows with Ab binding % > 90%, indicating
possible Persistently Infected BVD status or vaccine failures. Values shown
are for October Ab binding % in fresh milk with no Bronopol preservative pill.
Figure 2: Values of milk anti-p80 BVD Ab binding % from fresh milk
samples with no Bronopol preservative pill collected at consecutive DHIA
tests 35 days apart from the same cows. Correlation was r = 0.68 be­
tween the 2 months.
4 cows >90% BVD% the first month were retested the second month,
10/11 cows >90% the second month had been tested the month before)
and none were >90% BVD% both times. During the month other than
when they were >90%, their BVD% ranged from 18% to 77%, with most
less than 55%, except for one cow whose BVD% was 97%, then 87%.
At the time of the second test, the latter cow was 118 DIM, her daily
J Veterinar Sci Technolo
ISSN: 2157-7579 JVST, an open access journal
milk was 40 kg, with 305 day age, and season and fat corrected mature
equivalent (305ME) projected milk production of 11,604 kg. For all 15
cows at the time >90% BVD%, means were 107 DIM (range 41 – 188
DIM), daily milk 44 kg, 305ME 12,896 kg. All cows tested during either
month with valid DHIA milk production data (those not too fresh to
test or with missing milk weights; n= 496) had mean 305ME 13,450 kg.
BVD antigen capture ELISA using ear notch testing was negative for
PI status from all 345 cows tested, including all 279 cows whose milk
was also tested.
General linear models were used to determine which cow
characteristics might be significantly associated with BVD% and
305ME milk production (outcome variables). Three outliers were
Volume 3 • Issue 1 • 1000114
Citation: Wilson DJ, Rood KA, Goodell GM (2012) Bovine Viral Diarrhea Milk ELISA Test Detecting Anti-p80 Antibody – Association with Milk
Handling Methods and Cow Characteristics. J Veterinar Sci Technol 3:114. doi:10.4172/2157-7579.1000114
Page 4 of 5
found in the 305ME model, and while they did not change results,
outliers were nevertheless excluded.
The final GLM for BVD% included stage of lactation as defined
by ranges of DIM (1-9, 10-30, 31-60, 61-150, 151-300, 301-360,
>360 DIM) and daily milk production on test day. The model only
moderately explained variation among cows in BVD% (R2 = 0.23), but
was significant (P < 0.001). The BVD% means for cows within some
ranges of DIM were significantly different from each other as follows:
1-9 DIM (15.7%) and 10-30 DIM (33.9%) were different from each
other but were both lower than for all other stages of lactation, 61-150
DIM (60.0%) was higher than for every other stage of lactation (P <
0.05, ANOVA, Tukey’s) (Table 1 and Figure 5). This indicates that
anti-BVD Ab in cows’ milk was relatively high for the first month after
calving, and decreased to relatively low Ab at mid-lactation. The GLM
also detected a significant but numerically small negative association
between daily milk production and anti-BVD Ab in milk.
Indeed, in the 15 cows found with >90% BVD% (low anti-BVD
Ab), the effect of increasing stage of lactation indicated by the GLM is
partially evident. Eleven of the 15 low anti-BVD Ab cows were found
during the second month of the study; 10 had been tested the previous
month and none had >90% BVD% then. Their mean DIM increased
from 91 to 119 days, and their median DIM increased from 74 to 88
days. However, all 4 cows with low anti-BVD Ab during the first month
were re-tested and none repeated with >90% BVD% during the second
month, increasing in anti-BVD Ab while their mean DIM increased
from 116 to 151 days, and their median DIM increased from 108 to
143 days.
The final GLM for 305ME projected milk production included
DIM, lactation number, daily milk production on test day, and BVD%.
The model explained much of the variation among cows in 305ME (R2 =
Table 1: Mean milk anti-p80 BVD Ab binding % from fresh milk samples with no
Bronopol preservative pill for 491 cows in different stages of lactation (ranges of
days in milk).
BVD% binding means by ranges of days in milk
DIM Range
BVD%
n
1-9
15.7a
8
Standard deviation
13.4
10-30
33.9b
34
21.0
31-60
46.4d
53
22.9
61-150
60.0c
149
21.2
151-300
47.4d
185
21.2
301-360
40.5d
37
23.5
> 360
46.1d
25
24.8
Means with the same superscript letter are not significantly different from each
other, α = 0.05, ANOVA, Tukey’s.
Table 2: General linear model for cow characteristics associated with 305 day pro­
jected milk production (kg) corrected for age, season and fat.
Parameter
Estimate*
Standard Error t Value
Pr > t
Intercept
5677
424.0
13.4
< 0.001
Days in milk
10
0.9
11.9
< 0.001
Lactation
number
-554
82.6
-6.7
< 0.001
Daily Milk†
82
3.5
23.9
< 0.001
BVD%‡
-12
4.4
-2.8
0.005
* Estimated effects on 305 day milk production shown in kg
† Effect of each 0.45 kg increase in daily milk production at the time of DHIA test
‡ effect of each one percent increase in anti-p80 BVD Ab binding % (increased
binding indicates less anti-p80 BVD Ab in cow’s milk)
R2 = 0.72, P < 0.0001
J Veterinar Sci Technolo
ISSN: 2157-7579 JVST, an open access journal
Figure 5: Mean milk anti-p80 BVD Ab binding % from fresh milk samples
with no Bronopol preservative pill for cows in different stages of lactation
(ranges of days in milk).
0.72), and was highly significant (P < 0.0001) (Table 2). Increased DIM,
higher milk production on test day and younger cows – particularly
those in 1st and 2nd lactation – were associated with higher 305ME milk.
When ranges of DIM or attempts to characterize the lactation curve
were fitted into the model, they were of less explanatory value than
DIM as a continuous variable. Similarly, when lactation number was
converted to categorical variables such as 1st and 2nd lactation vs. 3rd­
plus lactation, it was of less explanatory value than simply using cows’
actual number of lactations as a categorical ordinal value. Adjusting for
the above factors, increased BVD% (decreased anti-BVD Ab in milk)
was significantly associated with decreased milk production. Each onepercent increase in BVD% was associated with 12 fewer kg of milk per
lactation; e.g. if one cow had 50% more BVD% (less anti-BVD Ab) than
another, she would be expected to produce 600 kg less 305ME milk
adjusting for the other significant factors.
Discussion
The range of milk ELISA values of BVD% observed comprised
nearly the entire range of possible values from 0 to 100%, and they
were normally distributed. While BVD% values appeared similar
among methods of handling milk samples - fresh, preservative pilled,
refrigerated or frozen – they did differ statistically between 2 of the
methods. Values were also moderately correlated in the same cow
across the 2 consecutive monthly tests. The only type of milk sample
which detected any cows with >90% BVD% (low anti-BVD Ab) was
fresh milk with no preservative. This might seem to indicate that cows’
milk anti-BVD Ab was increased as milk samples degenerated (pilled or
frozen), which is not logical. What more likely occurred was that non­
specific binding to the p80 antigen-coated test wells, thus inhibiting
more of the secondary test kit Ab binding, was increased in the less
fresh and/or preserved milk samples [10].
Anti-BVD Ab in cows’ milk was relatively high for the first month
after calving, and decreased to relatively low levels by mid-lactation. As
time since BVD vaccination – administered at dry off and 15-21 DIM increased as lactation progressed, antibody against p80 antigen of BVD
decreased. This agrees with a previous report that antibody, which has
been characterized as important to protection against BVD, wanes as
time passes following vaccination, and that booster immunizations
are important to maintaining immunity against BVD in cattle [11].
When adjusted for age, stage of lactation and milk production on
the day of testing, cows with higher anti-BVD Ab milked better than
those with lower Ab. The association of individual cow BVD Ab with
Volume 3 • Issue 1 • 1000114
Citation: Wilson DJ, Rood KA, Goodell GM (2012) Bovine Viral Diarrhea Milk ELISA Test Detecting Anti-p80 Antibody – Association with Milk
Handling Methods and Cow Characteristics. J Veterinar Sci Technol 3:114. doi:10.4172/2157-7579.1000114
Page 5 of 5
milk production, especially in non-PI cows, has not been reported
previously.
Milk ELISA results for BVD did not consistently identify any cows
as PI or possible vaccine failures, because while approximately 5% of
the cows were detected with >90% BVD% (low anti-BVD Ab), none
of the cows repeated as low anti-BVD Ab animals on another monthly
DHIA test. Most of the low anti-BVD Ab cows were detected during
the second monthly test, as they progressed from about the 3rd to 4th
month of lactation, which might be expected with waning antibody
as time passed since vaccination. However, this does not explain why
all cows with >90% BVD% during the first month did not persist into
the second month, instead re-testing with higher anti-BVD Ab as they
progressed from about the 4th to 5th month of lactation.
The detection and elimination of all PI animals does not guarantee
BVD-free status in dairy herds even if they are completely closed to
purchased animals. The view that closed herds “cannot develop BVD
infections” is being reevaluated. Some countries with national BVD
control programs and excellent records have found that approximately
10% of herds that have been certified free of BVD based on testing of
all calves born “relapse” (i.e. new BVD-positive animals are discovered)
each year even if the herds are isolated from other animals [2]. There
are several known mechanisms for how this can happen. In fecal
material, BVD virus has been shown to survive for at least 3 weeks.
Documented spread of BVD virus has occurred by flies, nose tongs,
and contaminated rubber stoppers on vials of vaccine (rubber stoppers
were allowed to dry and looked visibly clean), occupation of a pen
previously occupied by a PI calf for up to 1 day after its removal, and by
ambient air over a distance of 10 m [12].
Nevertheless, detection and removal of all PI animals remains the
single BVD control measure with the most demonstrated effectiveness
at reducing or eliminating the disease from dairy herds [2,9]. In the
present study, the finding of no PI cows by the milk ELISA test agreed
with the results of the antigen capture ear notch ELISA performed
concurrently, but the lack of repeatability from month to month in the
status of cows identified as PI or vaccine failure suspects as described
above suggests a limitation of the practical application of the milk
ELISA test. Another limitation of the milk test is that animals could
not be tested until they are approximately 2 years old, when they first
become lactating cows.
Where the milk BVD test might be most beneficial to the dairy
industry would be as a practical and convenient test for screening herd
replacements, especially when large numbers of lactating cows are
purchased and mixed into different production groups throughout a
dairy herd. Further study, including testing of cows diagnosed as BVD
PI according to the antigen capture ear notch ELISA, is needed to
evaluate this BVD ELISA test.
Acknowledgements
The authors thank the ownership and staff of the cooperating dairy farm,
Rocky Mountain DHIA, Idexx Laboratories, and the staff at the Utah Veterinary
Diagnostic Laboratory, AgSource Laboratories and The Dairy Authority.
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J Veterinar Sci Technolo
ISSN: 2157-7579 JVST, an open access journal
Volume 3 • Issue 1 • 1000114